package main
import(
	"fmt"
)

func swap(a *int,b *int){
	fmt.Printf("before a=%d b=%d\n",*a,*b)
	*a,*b = *b,*a
	fmt.Printf("after a=%d b=%d\n",*a,*b)
}
func main()  {
	var a int = 10
	var b int = 20
	swap(&a,&b)
	fmt.Printf("in main a=%d b=%d\n",a,b)
}
